Leptospirosis and scrub typhus, while significant causes of acute febrile illness in endemic regions, rarely lead to cardiac complications in children. This case report presents a unique instance of a 13-year-old previously healthy female who developed hypotension and sinus bradycardia during an episode of leptospirosis, which was successfully treated with doxycycline. However, the weeks following this initial episode saw the persistence of bradycardia, syncope, and left-sided chest pain, leading to a cardiology evaluation. Despite the absence of conduction block in serial ECGs and Holter monitoring, her symptoms continued until a second febrile episode—scrub typhus—again triggered symptomatic bradycardia. The patient responded well to doxycycline and a short course of corticosteroids, with complete resolution of symptoms and normalization of heart rate. This case highlights the potential of sequential tropical infections to precipitate functional sinus node disturbances in children and underscores the importance of including reversible infectious causes in the differential diagnosis of pediatric bradyarrhythmias.
Leptospirosis and scrub typhus are significant public health concerns in tropical countries, often presenting as undifferentiated febrile illnesses. These zoonotic infections, although epidemiologically distinct, share overlapping clinical features and geographic distribution, particularly in South and Southeast Asia. While both conditions are known to cause multisystem involvement, cardiac complications remain relatively uncommon and are frequently underdiagnosed, especially in children.
Leptospirosis, caused by pathogenic spirochetes of the genus Leptospira, is typically acquired through exposure to contaminated water and can manifest along a broad clinical spectrum—from a mild febrile illness to severe multi-organ dysfunction involving the renal, hepatic, pulmonary, and cardiovascular systems (1,2). Cardiac involvement in leptospirosis may include electrocardiographic abnormalities such as atrioventricular conduction delays, nonspecific ST-T changes, and sinus bradycardia, often without overt myocarditis (3,4). In rare instances, severe sinus bradycardia has been documented, potentially requiring intervention (5).
Scrub typhus, caused by Orientia tsutsugamushi and transmitted via chigger mite bites, is another leading cause of acute febrile illness in endemic areas. While it primarily targets the vascular endothelium and reticuloendothelial system, it can also lead to cardiovascular involvement, including myocarditis, pericardial effusion, and rhythm disturbances. Though rare, persistent sinus node dysfunction and sick sinus syndrome requiring pacing have been reported following scrub typhus infection (6,7).
This report describes the case of an adolescent female who developed recurrent symptomatic bradycardia following two separate episodes of tropical infections—first leptospirosis, followed by scrub typhus. The case highlights an unusual clinical course marked by persistent sinus bradycardia, syncopal events, and recovery without structural cardiac disease. It underscores the need for greater awareness of potential cardiac sequelae in pediatric tropical infections and emphasizes the importance of close ECG monitoring during and after the acute illness, as early recognition and appropriate management can significantly improve patient outcomes.
A 13-year-old female with no prior comorbidities presented to the emergency department with a one-month history of insidious-onset abdominal pain localised to the periumbilical region. The pain was dull, non-radiating, continuous, and aggravated in the early morning, with partial relief after food intake. Associated symptoms included dysuria, white vaginal discharge, decreased appetite, and reduced oral intake. Two days prior to admission, she developed a high-grade fever (101–102°F) with chills and rigours, followed by dizziness and a syncopal episode. There were no complaints of vomiting, diarrhoea, rash, respiratory symptoms, or bleeding manifestations.
At presentation, the child was conscious but hypotensive (BP 86/48 mmHg), bradycardic (HR 53/min), and had cold peripheries. Clinical examination revealed a soft abdomen with mild right hypochondrial tenderness but no guarding or organomegaly. Cardiovascular and respiratory system examinations were unremarkable except for bradycardia. An initial ECG showed sinus bradycardia. A screening 2D echocardiogram revealed structurally normal heart anatomy with mild physiological pulmonary regurgitation. Laboratory evaluation showed normal renal and hepatic function, with negative blood and urine cultures. Dengue, malaria, and typhoid serologies were negative. Leptospira IgM was positive, confirming the diagnosis of leptospirosis with decompensated shock. She was managed with inotropes and intravenous fluids and initiated on doxycycline, leading to clinical improvement. She was discharged after stabilization and advised to close outpatient follow-up.
In the subsequent weeks, the child developed persistent bradycardia along with left-sided chest pain, recurrent headaches, and intermittent episodes of syncope. She was followed up in the pediatric cardiology clinic. Serial ECGs revealed sinus bradycardia with no evidence of heart block. Given the suspicion of intermittent complete heart block or junctional escape rhythm, 24-hour Holter monitoring was conducted, which did not demonstrate any significant arrhythmias, pauses, or conduction abnormalities. A repeat echocardiogram remained normal. Given her ongoing symptoms, she was empirically started on oral prednisolone and orciprenaline, with close monitoring.
Approximately six weeks after the initial episode, the child presented again with a fever for three days, associated with vomiting (non-projectile, non-bilious), unilateral (left-sided) headache, and a 30-minute episode of loss of consciousness. There were no seizure-like features, no urinary or faecal incontinence, and no post-ictal confusion. On detailed history, it was revealed that the child had missed orciprenaline doses for two days prior to this episode due to poor oral intake during febrile illness. On examination, she was conscious and alert (GCS 15/15) with stable perfusion, although bradycardia persisted. Systemic examination remained within normal limits. Repeat ECG showed sinus bradycardia without conduction block
Figure 1. Electrocardiogram (ECG) of the patient showing sinus bradycardia with a ventricular rate of 53 beats per minute. The PR interval is 129 ms, QRS duration 78 ms, and QT/QTc interval 428/402 ms. No acute ST–T segment changes are evident. Normal QRS axis and morphology are seen across the limb and precordial leads.
Further investigations revealed elevated inflammatory markers and a repeat fever workup was negative for malaria, dengue, and Widal test. However, scrub typhus IgM was found to be positive, confirming the diagnosis of scrub typhus with symptomatic bradycardia. The patient was initiated on doxycycline, which led to the resolution of fever and a gradual improvement in heart rate. The successful treatment and the patient's subsequent stable condition bring hope and optimism in the face of such a complex case.
She continued follow-up in the pediatric cardiology clinic. Steroids were gradually tapered and discontinued in November 2024, followed by cessation of orciprenaline. Over the next several months, the child remained asymptomatic, with resolution of bradycardia
Figure 2. Electrocardiogram (ECG) showing resolution of sinus bradycardia in the same patient.
no further syncopal events, and complete return to normal activities, including school attendance. As of the latest follow-up, she demonstrates normal growth parameters, has no exertional intolerance, and continues to remain well without pharmacological support, highlighting the successful management and recovery in this case.
Consent
Leptospirosis and scrub typhus are significant public health concerns in tropical countries, often presenting as undifferentiated febrile illnesses. These zoonoses, although epidemiologically distinct, share overlapping clinical features and geographic distribution—particularly in South and Southeast Asia. While both pathogens may involve multiple organ systems, cardiac complications remain relatively uncommon and are frequently under-recognised, especially in children.
Leptospira interrogans infection is prevalent in monsoon-prone regions and usually manifests as a self-limiting fever; nevertheless, cardiovascular abnormalities—including atrial fibrillation, first-degree atrioventricular (AV) block, T-wave inversion and ST-segment changes—are well-described, whereas bradyarrhythmias are exceedingly rare (1,8). In the present child, unexplained sinus bradycardia and shock were noted during the leptospirosis phase without echocardiographic evidence of myocarditis or conduction block. A comparable presentation of bradycardia that resolved after doxycycline has been reported by Lashkarbolouk et al. (9).
Several weeks later, the child developed recurrent bradycardia with syncope during a new febrile episode. Serology confirmed Orientia tsutsugamushi. Although paediatric data are limited, reviews increasingly document cardiovascular involvement in scrub typhus, including myocarditis, pericardial effusion and rhythm disturbances (10,11). Arrhythmias—most often atrial fibrillation or conduction delays—may occur in up to one-quarter of severe cases (10). Persistent sinus node dysfunction is rare; Jung et al. described a sick-sinus syndrome necessitating permanent pacing after scrub typhus in an otherwise healthy adult (6).
In our case, recurrent bradycardia and syncope responded to orciprenaline and a short corticosteroid course, supporting an immune-mediated autonomic mechanism rather than irreversible nodal injury. The temporal relation between missed orciprenaline doses during fever and symptom recurrence further reinforces the concept of autonomic instability. Elevated inflammatory markers, absence of electrolyte derangements, and full recovery after antimicrobial and supportive therapy parallel earlier observations that cytokine-mediated myocardial irritability underlie transient rhythm disturbances in scrub typhus (11). Empirical steroid benefit, while anecdotal, echoes reports of selected patients with presumed immune-mediated myocarditis or refractory bradyarrhythmias. (12,13).
This sequential dual-infection scenario underscores that the cardiac conduction system can be a target organ in leptospirosis and scrub typhus. To our knowledge, it is among the first paediatric reports documenting persistent symptomatic bradycardia in consecutive infections with these two endemic pathogens in the absence of structural heart disease or congenital predisposition. Awareness of such presentations and vigilant ECG monitoring during and after illness is crucial for timely recognition and management.
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